A. Catalyzed Oxidations of Tertiary Amines
Beckwith et al., "Amine Autoxidation in Aqueous Solution," Aust. J. Chem., Vol. 36, (1983), pp. 719-39, discloses the autoxidation of various tertiary amines, including N-methylpyrolidine, N-methylpyridine, N-methylmorpholine, and N-dimethylbenzylamine in dimethylsulfoxide at 55.degree. C. for 0.5 hours catalyzed by the sodium salt of 1,2-naphthaquinone-4-sulfonic acid. Uncatalyzed autooxidations of various tertiary amines including N-methylpyrrolidine, N-methylpyridine, and N-dimethylbenzylamine in water at 55.degree. C. are also disclosed.
U.S. Pat. No. 4,264,776 to Hershman et al., issued Apr. 28, 1981, discloses the oxidation of tertiary amines in the presence of an activated carbon catalyst to prepare secondary amines. Temperatures employed are preferably in the range of from about 75.degree. to about 150.degree. C., with preferred oxygen partial pressures of from about 2 to about 7 kg/cm.sup.2 (about 30 to about 100 psi). This oxidation reaction can be carried out in water, i.e. an aqueous solvent system, over a wide range of pH, e.g. from 1 to 10 or so. In some instances, amine oxides are obtained along with the desired secondary amines (see column 11, lines 2-6). See Example I for 40% conversion of triethylamine to diethylamine plus an unspecified amount of triethylamine oxide.
B. Reactions involving octacyanomolybdate and tris-bypyridyl iron (III) salts
Chem. Abs. 97:144113q, 94:138942f, and 94:163272v, disclose the liquid phase oxidation of 1-nonene at 70.degree. C. in the presence of various cyanomolybdate salts, including K.sub.4 Mo(CN).sub.8. The rate of oxidation decreased in the order K.sub.4 Mo(CN).sub.4 &gt;K.sub.4 MoO(CN).sub.4 &gt;K.sub.4 MoO.sub.2 (CN).sub.4 &gt;K.sub.4 Mo(CN).sub.8.
Yamamoto et al., "Diethylbis(dipyridyl)iron: A Butadiene Cyclodimerization Catalyst", J. Am. Chem. Soc., Vol. 90, (1968), pp. 1878-83, discloses the dimerization of butadiene using a tris-bipyridyl iron (III) salt.
Fukuzumi et al., "Electron Transfer from Tetrakis(isocyanide)rhodium(I) Monomers, and the Oligomers to Iron (III) and Cobalt(III) Complexes: Enhancement of the Reactivity by the Oligomerization", Bull. Chem. Soc. Jpn., Vol. 55, (1982), pp. 3482-90, discloses the electron transfer reactions of tetrakis(isocyanide)rhodium (I) and oligomers thereof with tris-bipyridyl iron(III).
C. Preparation of amine oxides from tertiary amines using ozone or ozone derivatives and a molybdenum catalyst
U.S. Pat. No. 3,657,251 to Smetana, issued Apr. 18, 1972 discloses the selective preparation of amine oxides from tertiary amines including pyridines. The tertiary amine is contacted with an organic ozone derivative in the presence of a molybdenum, tungston or vanadium oxide forming catalyst. Suitable molybdenum catalysts include molybdenum hexacarbonyl, molybdenum trioxide and dioxide, sodium molybdate and the like.
U.S. Pat. No. 3,332,999 to Mitchell et al., issued July 25, 1967, discloses the preparation of amine oxides by the oxidation of tertiary amines with ozone in the presence of lower alcohols as a reaction medium at a temperature of from about 1.degree. to about 40.degree. C. The ozone is frequently used with a carrier gas such as air. A Lewis acid catalyst can be used, preferably the halides of metals such as chromium.